Throttling of AAA (RADIUS) Records
The Throttling of AAA (RADIUS) Records feature supports throttling of access (authentication and authorization) and accounting records that are sent to the RADIUS server. This feature allows a user to configure the appropriate throttling rate to avoid network congestion and instability; such as when there is insufficient bandwidth to accommodate a sudden burst of records generated from the Cisco IOS router to the RADIUS server.
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for Throttling of AAA (RADIUS) Records" section.
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Contents
•Information About Throttling of AAA (RADIUS) Records
•How to Configure Throttling of AAA (RADIUS) Records
•Configuration Examples for Throttling of AAA (RADIUS) Records
•Feature Information for Throttling of AAA (RADIUS) Records
Information About Throttling of AAA (RADIUS) Records
To configure the Throttling of AAA (RADIUS) Records feature, you should understand the following concepts:
•Benefits of the Throttling of AAA (RADIUS) Records Feature
•Throttling Access Requests and Accounting Records
Benefits of the Throttling of AAA (RADIUS) Records Feature
A Network Access Server (NAS), acting as RADIUS client, can generate a burst of accounting or access requests, causing severe network congestion or causing the RADIUS server to become overloaded with a burst of RADIUS traffic. This problem could be compounded when multiple NASs interact with the RADIUS servers.
The following conditions can trigger a sudden burst of RADIUS traffic:
•An interface flap, which in turn brings down all the subscriber sessions and generates accounting requests for each subscriber.
•The Cisco IOS High Availability (HA) program generating a START record for every session that survived a switchover, such as the scenario described the preceding bullet.
A large number of generated requests can make the network unstable if there is insufficient bandwidth or if the RADIUS server is slow to respond. Neither the User Datagram Protocol (UDP) transport layer nor the RADIUS protocol has a flow control mechanism. The throttling mechanism provided by this feature provides a solution for these issues.
Throttling Access Requests and Accounting Records
The Throttling of AAA (RADIUS) Records feature introduces a mechanism to control packets (flow control) at the NAS level, which improves the RADIUS server performance.
Because of their specific uses, access requests and accounting records must be treated separately. Access request packets are time sensitive, while accounting record packets are not.
•If a response to an access request is not returned to the client in a timely manner, the protocol or the user will time out, impacting the device transmission rates.
•Accounting records packets are not real-time critical.
When configuring threshold values on the same server, it is important to prioritize threshold values for the handling of the time-sensitive access request packets and to place a lesser threshold value on the accounting records packets.
In some cases, when an Internet Service Provider (ISP) is using separate RADIUS servers for access requests and accounting records, only accounting records throttling may be required.
Summary
•The Throttling of AAA (RADIUS) Records is disabled, by default.
•Throttling functionality can be configured globally or at server group level.
How to Configure Throttling of AAA (RADIUS) Records
This section describes how to configure throttling of access (authentication and authorization) and accounting records that are sent to the RADIUS server for both, global and server groups.
Server-group configurations are used to enable or disable throttling for a particular server group and to specify the threshold value for that server group.
Note Server-group configurations override any configured global configurations.
This section includes the following tasks.
•Throttling Accounting and Access Request Packets Globally
•Throttling Accounting and Access Request Packets Per Server Group
Throttling Accounting and Access Request Packets Globally
To globally configure the throttling of accounting and access request packets, perform the following task.
SUMMARY STEPS
1. enable
2. configure terminal
3. radius-server throttle {[accounting threshold] [access threshold [access-timeout number-of-timeouts]]}
4. exit
DETAILED STEPS
Throttling Accounting and Access Request Packets Per Server Group
The following server-group configuration can be used to enable or disable throttling for a specified server group and to specify the threshold value for that server group.
To configure throttling of server-group accounting and access request packets, perform the following task.
SUMMARY STEPS
1. enable
2. configure terminal
3. aaa group server radius server-group-name
4. throttle {[accounting threshold] [access threshold [access-timeout number-of-timeouts]]}
5. exit
DETAILED STEPS
Configuration Examples for Throttling of AAA (RADIUS) Records
This section provides the following configuration examples:
•Throttling Accounting and Access Request Packets Globally: Example
•Throttling Accounting and Access Request Packets Per Server Group: Example
Throttling Accounting and Access Request Packets Globally: Example
The following example shows how to limit the number of accounting requests sent to a server to 100:
enable
configure terminal
radius-server throttle accounting 100
The following example shows how to limit the number of access requests packets sent to a server to 200 and sets the number of time-outs allowed per transactions to 2:
enable
configure terminal
radius-server throttle access 200
radius-server throttle access 200 access-timeout 2
The following example shows how to throttle both accounting and access request packets:
enable
configure terminal
radius-server throttle accounting 100 access 200
Throttling Accounting and Access Request Packets Per Server Group: Example
The following example shows how to limit the number of accounting requests sent to server-group-A to 100:
enable
configure terminal
aaa group server radius server-group-A
throttle accounting 100
The following example shows how to limit the number of access requests packets sent to server-group-A to 200 and sets the number of time-outs allowed per transactions to 2:
enable
configure terminal
aaa group server radius server-group-A
throttle access 200 access-timeout 2
The following example shows how to throttle both accounting and access request packets for server-group-A:
enable
configure terminal
aaa group server radius server-group-A
throttle accounting 100 access 200
Additional References
The following sections provide references related to the Throttling of AAA (RADIUS) Records feature.
Related Documents
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AAA and RADIUS |
Cisco IOS Security Configuration Guide: Securing User Services, Release 15.0. |
Standards
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No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature. |
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MIBs
RFCs
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No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature. |
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Technical Assistance
Feature Information for Throttling of AAA (RADIUS) Records
Table 1 lists the release history for this feature.
Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS and Catalyst OS software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Note Table 1 lists only the Cisco IOS software release that introduced support for a given feature in a given Cisco IOS software release train. Unless noted otherwise, subsequent releases of that Cisco IOS software release train also support that feature.